Using skin biopsies, skin chambers and antigen inhalation challenge we have been investigating the relationship between cellular inflammatory responses and mediato production during ongoing immediate hypersensitivity responses in humans. We have found that i.v. steroids act to inhibit the ingress of eosinophils into tissues during allergic inflammatory responses. Furthermore, steroids inhibit total leukocyte histamine release by decreasing the amount of histamine rich cells in the circulation, having no effect on the amount of histamine in the cell or at the tissue site. To further investigate the cellular inflammatory responses, we have developed a skin chamber technique. We have been able to measure local increases in histamine release after ragweed administration in sensitive subjects. Concomitantly, we have further characterized the neutrophil chemotactic activity (NCA) appearing in the circulation after antigen mediated bronchospasm in humans. NCA is increased 1 minute after antigen administration, peaks at 10 minutes and persists for 24 hours. NCA is significantly correlated with the amount of antigen administered and degree of bronchospasm produced and can be inhibited by prior disodium cromoglycate administration. NCA is of very high molecular weight (greater than 900,000) and chemotactic only for neutrophils. Finally, we have demonstrated simultaneous appearance of histamine in the circulation after antigen induced bronchospasm. Future plans involve the search for local production of NCA at skin chamber sites, assessment of mediator production after pharmacologic blockade of the local and systemic allergic responses, and correlation of mediator production with in vitro and in vivo observed cellular responses.